Lactone polymers. I. Glass transition temperature of poly‐ε‐caprolactone by means on compatible polymer mixtures

Abstract

Abstract Dynamic mechanical properties determined with a torsion pendulum were used to ascertain the glass transition temperature T g of poly‐ε‐caprolactone. By measurements on compatible blends of poly‐ε‐caprolactone and poly(vinyl chloride), the T g of amorphous poly‐ε‐caprolactone was shown to be 202°K at about 1 cps. This is 16°K lower than the T g of annealed, crystalline polymer. The blend transition data were well fitted by both the Fox and the Gordon‐Taylor expressions. The Fox expression was also used to describe the decrease from 233°K of the secondary low‐temperature relaxation due to poly(vinyl chloride) by assuming the low temperature relaxation of poly‐ε‐caprolactone, 138°K, was responsible for the decrease in the blends. The 138°K relaxation due to poly‐ε‐caprolactone was decreased when more than 50% poly(vinyl chloride) was present.